Crosslinked vinylpyrrolidone polymeric powder has been prepared by rapid proliferous polymerization at high temperatures as described, for example, in U.S. Pat. No. 5,391,668. U.S. Pat. Nos. 5,089,910; 5,130,388 and 5,015,708 also describe processes for crosslinking vinyl lactam polymers to produce a powdery product. More recently, processes for free radical initiated polymerization and crosslinking of N-vinyl lactam monomers and comonomers have been developed which produce substantially solid formed or molded hydrogel products. These processes are described in U.S. Pat. Nos. 5,280,049; 5,362,796 and 5,354,823; however the products produced therein do not provide flowable hydrogels composed of micronized particles.
Accordingly, it is an object of the present invention to produce a crosslinked N-vinyl lactam polymer in a unique form such as a flowable micronized hydrogel suitable as a carrier for cosmetically and/or pharmaceutically active compounds in a cream, lotion or ointment formulation or as a moisturizer applied directly to the skin or hair.
Another object is to provide a liquid film for easily releasable wound dressings which extend the efficacy of the medicament over longer periods of treatment.
Still another object is to provide an economical and commercially feasible process for producing a crosslinked N-vinyl lactam polymer in a flowable, homogenized form composed of microparticles.
These and other objects of this invention will become apparent from the following description and disclosure.